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Readout frequency

The foreseen trigger rate of 10 tex2html_wrap_inline3186 events/sec allows 10 tex2html_wrap_inline2278 sec readout time per event. In addition, with the beam specifications proposed (5 tex2html_wrap_inline2708 10 tex2html_wrap_inline2648 ptc/sec spread over a 1 cm tex2html_wrap_inline2256 area), we expect a rather low occupancy.

The time needed to readout a full chip (according to the RD20 design) is of 4, 8 or 16 tex2html_wrap_inline2278 sec with the clock of 40, 20 or 10 MHz respectively.

Consequently 40 MHz and 20 MHz readout frequencies will not cause any dead time. But using 10 MHz clock would make us loose all features of the RD20 chip and cause 16 tex2html_wrap_inline2278 sec dead time.

A possible solution would be to use 20 MHz clock and 100 nsec peaking time. The use of a deconvolution algorithm would guarantee a time resolution of tex2html_wrap_inline2848 50 nsec [29]. In this situation we would have 2-3 beam particles recorded per event and a double interaction recorded in 5% of the cases.

Lars Schmitt
Wed May 22 16:44:09 METDST 1996